// ****************************************************************************

// ****************************************************************************

/*

piSetVolControl:

Simple app to set volume using ALSA controls.

Copyright 2015 by Darren Faulke <darren@alidaf.co.uk>

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation, either version 2 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program. If not, see <http://www.gnu.org/licenses/>.

*/

// ****************************************************************************

// ****************************************************************************

#define Version "Version 0.2"

// Compilation:

//

// Compile with gcc piSetVolControl.c -o piSetVolControl -lasound

// Also use the following flags for Raspberry Pi optimisation:

// -march=armv6 -mtune=arm1176jzf-s -mfloat-abi=hard -mfpu=vfp

// -ffast-math -pipe -O3

// Authors: D.Faulke 19/10/15

// Contributors:

//

// Changelog:

//

// v0.1 Initial version.

// v0.2 Added command line parameters.

//

#include <stdio.h>

#include <string.h>

#include <alsa/asoundlib.h>

#include <argp.h>

// ****************************************************************************

// argp documentation.

// ****************************************************************************

const char *argp_program_version = Version;

const char *argp_program_bug_address = "darren@alidaf.co.uk";

static char doc[] = "A short test program to set ALSA control values.";

static char args_doc[] = "alsavol <options>";

// ****************************************************************************

// Data definitions.

// ****************************************************************************

// Data structure to hold command line arguments.

struct structArgs

};

// ****************************************************************************

// Command line argument definitions.

// ****************************************************************************

static struct argp_option options[] =

{

{ 0, 0, 0, 0, "Card information:" },

{ "card", 'c', "<n>", 0, "Card ID number." },

{ "control", 'd', "<n>", 0, "Control ID number." },

{ 0, 0, 0, 0, "Control parameters:" },

{ "val", 'v', "<%>/<%,%>", 0, "Set control value(s)." },

{ 0 }

};

// ****************************************************************************

// Command line argument parser.

// ****************************************************************************

static int parse_opt( int param, char *arg, struct argp_state *state )

{

char *str;

char *token;

const char delimiter[] = ",";

struct structArgs *cmdArgs = state->input;

switch( param )

{

case 'c' :

cmdArgs->card = atoi( arg );

break;

case 'd' :

cmdArgs->control = atoi( arg );

break;

case 'v' :

str = arg;

token = strtok( str, delimiter );

cmdArgs->value1 = atoi( token );

token = strtok( NULL, delimiter );

if ( token == NULL )

cmdArgs->value2 = cmdArgs->value1;

else

cmdArgs->value2 = atoi( token );

break;

}

return 0;

};

// ****************************************************************************

// argp parser parameter structure.

// ****************************************************************************

static struct argp argp = { options, parse_opt, args_doc, doc };

// ****************************************************************************

// Main section.

// ****************************************************************************

void main( int argc, char *argv[] )

{

struct structArgs cmdArgs;

int errNum;

// ************************************************************************

// ALSA control elements.

// ************************************************************************

snd_ctl_t *ctl; // Simple control handle.

snd_ctl_elem_id_t *id; // Simple control element id.

snd_ctl_elem_value_t *control; // Simple control element value.

snd_ctl_elem_type_t type; // Simple control element type.

snd_ctl_elem_info_t *info; // Simple control info container.

// ************************************************************************

// Get command line parameters.

// ************************************************************************

argp_parse( &argp, argc, argv, 0, 0, &cmdArgs );

printf( "Card = %i\n", cmdArgs.card );

printf( "Control = %i\n", cmdArgs.control );

printf( "Value 1 = %i\n", cmdArgs.value1 );

printf( "Value 2 = %i\n", cmdArgs.value2 );

// ************************************************************************

// Set up ALSA control.

// ************************************************************************

sprintf( cmdArgs.deviceID, "hw:%i", cmdArgs.card );

printf( "Device ID = %s.\n", cmdArgs.deviceID );

if ( snd_ctl_open( &ctl, cmdArgs.deviceID, 1 ) < 0 )

{

printf( "Error opening control.\n" );

return;

}

// Initialise a simple control element id structure.

snd_ctl_elem_id_alloca( &id );

snd_ctl_elem_id_set_numid( id, cmdArgs.control );

// Initialise info element.

snd_ctl_elem_info_alloca( &info );

snd_ctl_elem_info_set_numid( info, cmdArgs.control );

// Is the control valid?

if ( snd_ctl_elem_info( ctl, info ) < 0 )

{

printf( "Error getting control element info.\n" );

return;

}

// Find type of control.

// either:

// SND_CTL_ELEM_TYPE_INTEGER,

// SND_CTL_ELEM_TYPE_INTEGER64,

// SND_CTL_ELEM_TYPE_ENUMERATED, etc.

// Only interested in INTEGER.

type = snd_ctl_elem_info_get_type( info );

if ( type != SND_CTL_ELEM_TYPE_INTEGER )

{

printf( "Control type is not integer.\n" );

printf( "Type = %s\n", type );

return;

}

// ************************************************************************

// Get some information for selected control.

// ************************************************************************

printf( "Min value for control = %d\n", snd_ctl_elem_info_get_min( info ));

printf( "Max value for control = %d\n", snd_ctl_elem_info_get_max( info ));

printf( "Step value for control = %d\n", snd_ctl_elem_info_get_step( info ));

// Initialise the control element value container.

snd_ctl_elem_value_alloca( &control );

snd_ctl_elem_value_set_id( control, id );

// ************************************************************************

// Set values for selected control.

// ************************************************************************

snd_ctl_elem_value_set_integer( control, 0, cmdArgs.value1 );

if ( snd_ctl_elem_write( ctl, control ) < 0 )

printf( "Error setting L volume" );

else

printf( "Set L volume to %d.\n", cmdArgs.value1 );

snd_ctl_elem_value_set_integer( control, 1, cmdArgs.value2 );

if ( snd_ctl_elem_write( ctl, control ) < 0 )

printf( "Error setting R volume" );

else

printf( "Set R volume to %d.\n", cmdArgs.value2 );

// ************************************************************************

// Clean up.

// ************************************************************************

snd_ctl_close( ctl );

return;

}